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  <div class="section" id="module-email.errors">
<span id="email-errors-exception-and-defect-classes"></span><h1><a class="reference internal" href="#module-email.errors" title="email.errors: The exception classes used by the email package."><code class="xref py py-mod docutils literal notranslate"><span class="pre">email.errors</span></code></a>: Exception and Defect classes<a class="headerlink" href="#module-email.errors" title="Permalink to this headline">¶</a></h1>
<p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.8/Lib/email/errors.py">Lib/email/errors.py</a></p>
<hr class="docutils" />
<p>The following exception classes are defined in the <a class="reference internal" href="#module-email.errors" title="email.errors: The exception classes used by the email package."><code class="xref py py-mod docutils literal notranslate"><span class="pre">email.errors</span></code></a> module:</p>
<dl class="exception">
<dt id="email.errors.MessageError">
<em class="property">exception </em><code class="sig-prename descclassname">email.errors.</code><code class="sig-name descname">MessageError</code><a class="headerlink" href="#email.errors.MessageError" title="Permalink to this definition">¶</a></dt>
<dd><p>This is the base class for all exceptions that the <a class="reference internal" href="email.html#module-email" title="email: Package supporting the parsing, manipulating, and generating email messages."><code class="xref py py-mod docutils literal notranslate"><span class="pre">email</span></code></a> package can
raise.  It is derived from the standard <a class="reference internal" href="exceptions.html#Exception" title="Exception"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Exception</span></code></a> class and defines no
additional methods.</p>
</dd></dl>

<dl class="exception">
<dt id="email.errors.MessageParseError">
<em class="property">exception </em><code class="sig-prename descclassname">email.errors.</code><code class="sig-name descname">MessageParseError</code><a class="headerlink" href="#email.errors.MessageParseError" title="Permalink to this definition">¶</a></dt>
<dd><p>This is the base class for exceptions raised by the
<a class="reference internal" href="email.parser.html#email.parser.Parser" title="email.parser.Parser"><code class="xref py py-class docutils literal notranslate"><span class="pre">Parser</span></code></a> class.  It is derived from
<a class="reference internal" href="#email.errors.MessageError" title="email.errors.MessageError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">MessageError</span></code></a>.  This class is also used internally by the parser used
by <a class="reference internal" href="email.headerregistry.html#module-email.headerregistry" title="email.headerregistry: Automatic Parsing of headers based on the field name"><code class="xref py py-mod docutils literal notranslate"><span class="pre">headerregistry</span></code></a>.</p>
</dd></dl>

<dl class="exception">
<dt id="email.errors.HeaderParseError">
<em class="property">exception </em><code class="sig-prename descclassname">email.errors.</code><code class="sig-name descname">HeaderParseError</code><a class="headerlink" href="#email.errors.HeaderParseError" title="Permalink to this definition">¶</a></dt>
<dd><p>Raised under some error conditions when parsing the <span class="target" id="index-0"></span><a class="rfc reference external" href="https://tools.ietf.org/html/rfc5322.html"><strong>RFC 5322</strong></a> headers of a
message, this class is derived from <a class="reference internal" href="#email.errors.MessageParseError" title="email.errors.MessageParseError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">MessageParseError</span></code></a>.  The
<a class="reference internal" href="email.message.html#email.message.EmailMessage.set_boundary" title="email.message.EmailMessage.set_boundary"><code class="xref py py-meth docutils literal notranslate"><span class="pre">set_boundary()</span></code></a> method will raise this
error if the content type is unknown when the method is called.
<a class="reference internal" href="email.header.html#email.header.Header" title="email.header.Header"><code class="xref py py-class docutils literal notranslate"><span class="pre">Header</span></code></a> may raise this error for certain base64
decoding errors, and when an attempt is made to create a header that appears
to contain an embedded header (that is, there is what is supposed to be a
continuation line that has no leading whitespace and looks like a header).</p>
</dd></dl>

<dl class="exception">
<dt id="email.errors.BoundaryError">
<em class="property">exception </em><code class="sig-prename descclassname">email.errors.</code><code class="sig-name descname">BoundaryError</code><a class="headerlink" href="#email.errors.BoundaryError" title="Permalink to this definition">¶</a></dt>
<dd><p>Deprecated and no longer used.</p>
</dd></dl>

<dl class="exception">
<dt id="email.errors.MultipartConversionError">
<em class="property">exception </em><code class="sig-prename descclassname">email.errors.</code><code class="sig-name descname">MultipartConversionError</code><a class="headerlink" href="#email.errors.MultipartConversionError" title="Permalink to this definition">¶</a></dt>
<dd><p>Raised when a payload is added to a <a class="reference internal" href="email.compat32-message.html#email.message.Message" title="email.message.Message"><code class="xref py py-class docutils literal notranslate"><span class="pre">Message</span></code></a> object
using <code class="xref py py-meth docutils literal notranslate"><span class="pre">add_payload()</span></code>, but the payload is already a scalar and the
message’s <em class="mailheader">Content-Type</em> main type is not either
<em class="mimetype">multipart</em> or missing.  <a class="reference internal" href="#email.errors.MultipartConversionError" title="email.errors.MultipartConversionError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">MultipartConversionError</span></code></a> multiply
inherits from <a class="reference internal" href="#email.errors.MessageError" title="email.errors.MessageError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">MessageError</span></code></a> and the built-in <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>.</p>
<p>Since <code class="xref py py-meth docutils literal notranslate"><span class="pre">Message.add_payload()</span></code> is deprecated, this exception is rarely
raised in practice.  However the exception may also be raised if the
<a class="reference internal" href="email.compat32-message.html#email.message.Message.attach" title="email.message.Message.attach"><code class="xref py py-meth docutils literal notranslate"><span class="pre">attach()</span></code></a>
method is called on an instance of a class derived from
<a class="reference internal" href="email.mime.html#email.mime.nonmultipart.MIMENonMultipart" title="email.mime.nonmultipart.MIMENonMultipart"><code class="xref py py-class docutils literal notranslate"><span class="pre">MIMENonMultipart</span></code></a> (e.g.
<a class="reference internal" href="email.mime.html#email.mime.image.MIMEImage" title="email.mime.image.MIMEImage"><code class="xref py py-class docutils literal notranslate"><span class="pre">MIMEImage</span></code></a>).</p>
</dd></dl>

<p>Here is the list of the defects that the <a class="reference internal" href="email.parser.html#email.parser.FeedParser" title="email.parser.FeedParser"><code class="xref py py-class docutils literal notranslate"><span class="pre">FeedParser</span></code></a>
can find while parsing messages.  Note that the defects are added to the message
where the problem was found, so for example, if a message nested inside a
<em class="mimetype">multipart/alternative</em> had a malformed header, that nested message
object would have a defect, but the containing messages would not.</p>
<p>All defect classes are subclassed from <code class="xref py py-class docutils literal notranslate"><span class="pre">email.errors.MessageDefect</span></code>.</p>
<ul>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">NoBoundaryInMultipartDefect</span></code> – A message claimed to be a multipart,
but had no <em class="mimetype">boundary</em> parameter.</p></li>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">StartBoundaryNotFoundDefect</span></code> – The start boundary claimed in the
<em class="mailheader">Content-Type</em> header was never found.</p></li>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">CloseBoundaryNotFoundDefect</span></code> – A start boundary was found, but
no corresponding close boundary was ever found.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.3.</span></p>
</div>
</li>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">FirstHeaderLineIsContinuationDefect</span></code> – The message had a continuation
line as its first header line.</p></li>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">MisplacedEnvelopeHeaderDefect</span></code> - A “Unix From” header was found in the
middle of a header block.</p></li>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">MissingHeaderBodySeparatorDefect</span></code> - A line was found while parsing
headers that had no leading white space but contained no ‘:’.  Parsing
continues assuming that the line represents the first line of the body.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.3.</span></p>
</div>
</li>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">MalformedHeaderDefect</span></code> – A header was found that was missing a colon,
or was otherwise malformed.</p>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 3.3: </span>This defect has not been used for several Python versions.</p>
</div>
</li>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">MultipartInvariantViolationDefect</span></code> – A message claimed to be a
<em class="mimetype">multipart</em>, but no subparts were found.  Note that when a message
has this defect, its <a class="reference internal" href="email.compat32-message.html#email.message.Message.is_multipart" title="email.message.Message.is_multipart"><code class="xref py py-meth docutils literal notranslate"><span class="pre">is_multipart()</span></code></a> method may
return <code class="docutils literal notranslate"><span class="pre">False</span></code> even though its content type claims to be <em class="mimetype">multipart</em>.</p></li>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">InvalidBase64PaddingDefect</span></code> – When decoding a block of base64
encoded bytes, the padding was not correct.  Enough padding is added to
perform the decode, but the resulting decoded bytes may be invalid.</p></li>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">InvalidBase64CharactersDefect</span></code> – When decoding a block of base64
encoded bytes, characters outside the base64 alphabet were encountered.
The characters are ignored, but the resulting decoded bytes may be invalid.</p></li>
<li><p><code class="xref py py-class docutils literal notranslate"><span class="pre">InvalidBase64LengthDefect</span></code> – When decoding a block of base64 encoded
bytes, the number of non-padding base64 characters was invalid (1 more than
a multiple of 4).  The encoded block was kept as-is.</p></li>
</ul>
</div>


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